Lidar-derived elevation data for Jago River permafrost research site, collected August 1, 2025

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Frequently anticipated questions:


What does this data set describe?

Title:
Lidar-derived elevation data for Jago River permafrost research site, collected August 1, 2025
Abstract:
Lidar-derived elevation data for Jago River permafrost research site, collected August 1, 2025, Raw Data File 2025-30, provides classified point cloud data, a digital surface model (DSM), a digital terrain model (DTM), and an intensity model derived from aerial lidar surveys. The data cover a permafrost study area adjacent to the Jago River in Northern Alaska. The Alaska Division of Geological & Geophysical Surveys (DGGS) conducted the work during snow‑free conditions. The data were acquired to support research on permafrost evolution and to provide baseline elevation information for monitoring environmental change. Aerial lidar data were collected on August 1, 2025, and ground control data were obtained between August 1-3, 2025. These data are provided as a Raw Data File under an open end-user license and are available on the DGGS website (http://doi.org/10.14509/31748).
Supplemental_Information:
boundaries:    A boundary, also known as an Area of Interest (AOI) or border, that defines the area covered by the data.	
classified_points:    Classified point cloud data are provided in LAZ format. Classification follows ASPRS 2025 standards with return and intensity values. Ground-classified points have a mean density of 41.1 pts/m2 and an average spacing of 15.6 cm.	
dsm:    The DSM represents surface elevations, including heights of vegetation and structures. The DSM is a single-band, 32-bit tiled GeoTIFF dataset of 10-cm resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum).	
dtm:    The DTM represents bare earth elevations, excluding vegetation and structures. The DTM is a single-band, 32-bit tiled GeoTIFF dataset of 10-cm resolution. No Data value is set to -3.40282306074e+38.	
footprints:    Footprints for tiled data.
lidar_intensity: The lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is (1) primarily a function of scanned object reflectance in relation to the signal frequency, (2) dependent on ambient conditions, and (3) not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit GeoTIFF file of 1-m resolution, with a No Data value set to -3.40282306074e+38.
  1. How might this data set be cited?
    Zechmann, J.M., Liljedahl, A.K., Wolken, G.J., Jorgenson, M.T., and Witharana, Chandi, 2025, Lidar-derived elevation data for Jago River permafrost research site, collected August 1, 2025: Raw Data File RDF 2025-30, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 15 p
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -143.779168
    East_Bounding_Coordinate: -143.553728
    North_Bounding_Coordinate: 69.767903
    South_Bounding_Coordinate: 69.717603
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 01-Aug-2025
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a raster data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 7
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -141
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest .00000001
      Ordinates (y-coordinates) are specified to the nearest .00000001
      Planar coordinates are specified in Meters
      The horizontal datum used is NAD83 (2011).
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: NAVD88, GEOID12B
      Altitude_Resolution: 0.500000
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    boundaries
    A boundary, also known as an Area of Interest (AOI) or border, that defines the area covered by the data. (Source: DGGS)
    classified_points
    Classified point cloud data are provided in LAZ format. Classification follows ASPRS 2025 standards with return and intensity values. Ground-classified points have a mean density of 41.1 pts/m2 and an average spacing of 15.6 cm. (Source: DGGS)
    dsm
    The DSM represents surface elevations, including heights of vegetation and structures. The DSM is a single-band, 32-bit tiled GeoTIFF dataset of 10-cm resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum). (Source: DGGS)
    dtm
    The DTM represents bare earth elevations, excluding vegetation and structures. The DTM is a single-band, 32-bit tiled GeoTIFF dataset of 10-cm resolution. No Data value is set to -3.40282306074e+38. (Source: DGGS)
    footprints
    Footprints for tiled data. (Source: DGGS)
    lidar_intensity
    The lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is (1) primarily a function of scanned object reflectance in relation to the signal frequency, (2) dependent on ambient conditions, and (3) not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit GeoTIFF file of 1-m resolution, with a No Data value set to -3.40282306074e+38. (Source: DGGS)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
    A subaward from the National Science Foundation, grant number 2234117, funded this work. We thank Alpine Air Alaska for their aviation expertise and for their contributions to these data products, and Toolik Field Station and Battelle ARO for providing logistical support. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.
  3. To whom should users address questions about the data?
    Alaska Division of Geological & Geophysical Surveys
    GIS Manager
    3354 College Rd
    Fairbanks, AK
    USA

    907-451-5020 (voice)
    dggsgis@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays

Why was the data set created?

The products were generated to support permafrost evolution research and to provide baseline elevation data for monitoring environmental change, including terrain morphology, thaw subsidence, and other indicators of permafrost degradation in Northern Alaska.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 03-Aug-2025 (process 1 of 3)
    Ground survey - On August 1, 2025, we established a GNSS base station at the field camp using a Trimble R12i to support subsequent correction of lidar survey flightlines. This location also served as the base station for ground control point collection. Ground control points were collected on August 1-3, 2025. We deployed a Trimble R12i GNSS base receiver and surveyed points with a rover Trimble R12i GNSS receiver/Mesa3 controller within the survey area. We collected 157 ground control points and checkpoints; ground control points were collected on bare earth (gravel), and checkpoints were taken in areas of bare earth, tundra vegetation, reeds, shrubs, and tussocks. Where possible, we surveyed existing markers (rock piles, tents, and barrels) to determine horizontal accuracy later.
    Date: 01-Aug-2025 (process 2 of 3)
    Aerial survey - DGGS used a Riegl VUX1-LR22 laser scanner with a global navigation satellite system (GNSS) and a Northrop Grumman LN-200C inertial measurement unit (IMU) integrated by Phoenix LiDAR Systems. The sensor can collect up to 1,500,000 points per second at a range of 230 m, or a minimum of 50,000 points per second at 1,000 m (ranges assume greater than 20 percent natural reflectance). The scanner operated with a pulse refresh rate of 1,500,000 pulses per second at a scan rate of 200 revolutions per second. We used a Robinson R44 helicopter to survey from an elevation of approximately 100-150 m above ground level, at a ground speed of approximately 30 m/s, and with a scan angle set from 120 to 240 degrees. The total survey area covers approximately 26.3 km2. The survey area was accessed by air from Toolik Field Station. Data were collected from 1:05 pm to 3:55 pm (AKST). The weather throughout the survey was clear with no wind.
    Date: 2025 (process 3 of 3)
    Dataset processing - We processed point data in Spatial Explorer for initial filtering and multiple-time-around (MTA) disambiguation. MTA errors, corrected in this process, result from ambiguous interpretations of received pulse time intervals and occur more frequently with higher pulse refresh rates. IMU and GNSS data were processed in Inertial Explorer, and flightline information was integrated with the point cloud in Spatial Explorer. We calibrated the point data at an incrementally precise scale of sensor movement and behavior, incorporating sensor velocity, roll, pitch, and yaw fluctuations throughout the survey. For the lidar data collection, the average pulse density is 150.3 pulses/m2, and the average pulse spacing is 8.2 cm. We created a macro (an ordered list of point classification commands tailored to this dataset) in Terrasolid software and classified points in accordance with the American Society for Photogrammetry & Remote Sensing (ASPRS) 2025 guidelines (ASPRS, 2025). Once classified, we applied a geometric transformation and converted the points from ellipsoidal heights to GEOID12B (Alaska) orthometric heights. Raster products were derived from the point cloud in ArcGIS Pro. A 10-cm DSM was interpolated from ground and vegetation classes using a binning method and maximum values. A 10-cm DTM was interpolated from all ground-class returns using a binning method and minimum values. We also produced a 10-cm intensity image using average binning in ArcGIS Pro, with no normalization or corrections applied.
  3. What similar or related data should the user be aware of?
    Wolken, G.J., Hendricks, K.A., Daanen, R.P., Overbeck, J.R., Stevens, D.S.P., and Masterman, S.S., 2017, Alaska & climate change: Information Circular IC 64, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 2 p

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Not applicable
  2. How accurate are the geographic locations?
    The offset between the pointcloud (visualized as a DSM hillshade or intensity image) and 20 ground control points was 2.2 cm measured west to east and 3.7 cm measured south to north. This was changed to -4.4 cm and +0.7 cm, respectively, by applying a constant horizontal correction. We used 17 checkpoints to determine the horizontal accuracy of the corrected point cloud by measuring the offset between checkpoints and their respective locations in the dsm and/or intensity image produced from the corrected point cloud. The project's horizontal accuracy has a root-mean-square error (RMSE) of 10.5 cm in the east-west direction and 8.3 cm in the north-south direction.
  3. How accurate are the heights or depths?
    We measured a mean elevation offset of -1.5 cm between 37 control points and the point cloud . This offset was changed to +1.8 cm in non-vegetated areas and +13.1 cm in vegetated areas by applying a constant vertical correction of +1.5 cm to the lidar point data. We used 37 non-vegetated and 67 vegetated checkpoints to determine the vertical accuracy of the point cloud ground class using a Triangulated Irregular Network (TIN) approach. The project's vertical accuracy has an RMSE of 8.7 cm in non-vegetated areas and 18.6 cm in vegetated areas. We evaluated the relative accuracy of this dataset using interswath overlap consistency and found a 5.7 cm RMSE.
  4. Where are the gaps in the data? What is missing?
    This is a full-release dataset. There was no over-collect.
  5. How consistent are the relationships among the observations, including topology?
    Data quality is consistent throughout the survey, save for gaps over bodies of water. Data were validated using commercial GIS software.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints:
This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  1. Who distributes the data set? (Distributor 1 of 1)
    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    Attn: Simone Montayne
    3354 College Road
    Fairbanks, AK
    USA

    907-451-5020 (voice)
    907-451-5050 (FAX)
    dggspubs@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (http://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set? RDF 2025-30
  3. What legal disclaimers am I supposed to read?
    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity, whether from the use of the electronic services or products, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requestor or anyone else exceed the fee paid for the electronic service or product.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 10-Dec-2025
Metadata author:
Simone Montayne
3354 College Road
Fairbanks, AK
USA

907-451-5020 (voice)
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.50 on Mon Dec 22 18:22:44 2025